I was just taking a look at
http://www.w3.org/2009/sparql/wiki/Feature:JavaScriptFunctions which was
submitted on our -comments list by Holger Knublauch of TopQuadrant.
The gist, as I understand it, is asking implementations to dereference
URIs of unknown FILTER functions to retrieve RDF descriptions that
contain JavaScript implementations of the functions.
I think this is pretty cool, myself, but it also seems very new, a very
high burden for implementors, and potentially fraught with security
concerns that I haven't thought of yet.
I'd like to know if there are any other implementations of this feature
(which, to generalize a bit, I'd call a mechanism for interoperably
resolving unknown SPARQL functions) and also if there are any Working
Group members who care to advocate in favor of the group producing a
specification for this feature.
Lee